A person is trapped after eight cars were involved in a crash with a truck on the M4 in Sydney's west.
Paramedics, police and fire crews are on the scene trying to free the motorist, with westbound lanes closed in Prospect at the Light Horse interchange.
9News understands the trapped person the van is stable and 18 other people, some with minor injuries, have been assessed by paramedics.
Many are making the nightly commute home and traffic has already banked up 10 kilometres back to Merrylands.
Motorists are being urged to avoid the area.
"Westbound traffic is heavy from Greystanes, while eastbound traffic is heavy from Eastern Creek," the Transport Management Centre said.